When typed word echo is enabled, NVDA collects typed characters in an internal buffer and speaks that buffer when the word ends (space, Enter, Tab, punctuation).
Any caret movement clears that buffer, including Backspace and Delete. So if you type a word, correct a mistake with Backspace and type the rest, NVDA only speaks the part typed after the correction.
This add-on reads the actual text before the caret from the edit control when the word ends and speaks the whole word instead. It works after Backspace, Delete, and corrections made with the arrow keys or the mouse.
NVDA Settings, "Whole word echo" category:
A toggle command is available in Input gestures, category "Whole word echo". No gesture is assigned by default.